The unique and distinctive flavor of fresh roasted and brewed coffee is due primarily to chemicals formed during roasting W. Baltes et al, J. Agric. Food Chem. 35(3): 340-6 (1987); W. Baletes et al, Z. Lebensm. Unters. Forsch. 184(3): 179-86 (1987); W. Baltes et al, Z. Lebensm. Unters. Forsch. 184(6): 478-84 (1987); W. Baltes et al, Z. Lebensm. Unters. Forsch. 185(1): 5-9 (1987); W. Baltes et al, Z. Lebensm. Unters. Forsch. 184(6): 485-93 (1987); R. J. Clarke, Coffee, Vol. 2 Technology. Clarke and Macrae ed. 1987 Dept. Food Science, University of Reading. Reading; I. Flament and C. Chevallier. "Analysis of Volatile Constituents of Coffee Aroma." Chem. Ind. (London).: 1988; R. Tressl, "Formation of Components in Roasted Coffee." Thermal Generation of Aromas. Parliment ed. 1989 American Chemical Society. Washington, D.C. As green coffee beans are roasted, amino acids, sugars, lipids and lignin in the bean degrade and react with each other to form thousands of mostly odorless compounds. Among these are a small subset of odor-active compounds. The chemical structures of some of these odors are known but most have yet to be described or at least the relative odor importance of the known components have yet to be demonstrated. What is generally accepted is that the aroma of coffee immediately after roasting is at its most desirable state. Within a few days the amount of desirable aroma has decreased noticeably and many undesirable odors have become detectable. The chemistry of this flavor change may involve free radical reactions similar to those that formed the flavor during roasting.
The odor-active chemicals in coffee are formed under reductive conditions and are therefore susceptible to oxidation. Because oxidized coffee aroma is generally undesirable, oxidation is the most obvious reaction to inhibit; however, oxygen is not the only agent involved in the degradation of fresh roasted coffee aroma. The inevitable decay of nitrogen packed coffee is a perfect example of this chemistry Thus, there are two problems to be solved in order to prepare a stable coffee essence. The desirable aromas must be trapped and stabilized and at the same time the undesirable odors must be either eliminated or their formation prevented.
Instant coffee beverage dispensers have been known for some time and are useful in vending machines, restaurants and institutions where it is less than desirable to make freshly brewed coffee. However, not withstanding the widespread use of such coffee beverage machines, the beverage product dispensed using a liquid coffee concentrate suffers from the disadvantage that flavor and aroma of such beverage is quite different from the flavor and aroma associated with the flavor and aroma of freshly brewed or freshly ground coffee. The present invention relates to preparing and isolating these gaseous flavors and aromas and their use in making improved beverages and foods therefrom.